1. Field of the Invention.
The present invention relates to an insulation-displacement terminal fitting.
2. Description of the Related Art.
A known insulation-displacement terminal fitting is disclosed in published European Patent Appl. No. EP 0 722 197 A2 and has opposed first and second side walls with a wire receiving space therebetween. First and second insulation-displacement portions project from the respective first and second side walls and into the wire-receiving space. The known insulation-displacement terminal fitting is used with a wire that has a conductive core surrounded by a resin coating. The wire can be pushed normal to its longitudinal direction and into the wire-receiving space. As a result, the insulation-displacement portions cut open the resin coating and contact the core of the wire.
The insulation-displacement portions disclosed in the above-referenced EP 0 722 197 A2 are formed by bending or embossing portions of the side walls into a V-shape or triangular shape when viewed in a wire pushing direction. Thus, a pulling force in the longitudinal direction of the connected wire does not deform the blades of the insulation-displacement portions, and a loose movement of the wire in the longitudinal direction can be prevented.
However, V-shaped insulation-displacement portions contact the resin coating over a larger area than an insulation-displacement portion that is in the form of a single plate. Thus, it is more difficult to cut open the resin coating with a V-shaped insulation-displacement portion. A resin coating that is not cut open may be hooked on the insulation-displacement portions and may be stretched elastically as the core is inserted between the insulation-displacement portions. Elastic restoring forces of the stretched resin coating will urge the wire in a direction to withdraw the core from the clearance between the insulation-displacement portions. Alternatively, a resin coating that is not cut may be pushed between the insulation-displacement portions together with the core. Accordingly, the resin coating may prevent the core from properly contacting the insulation-displacement portions.
In view of the above, an object of the present invention is to provide an insulation-displacement terminal fitting with insulation-displacement portions that can restrict a loose movement of a wire in its longitudinal direction and securely cut open a coating of the wire.
The invention is directed to an insulation-displacement terminal fitting with first and second opposed side walls and a wire-receiving space therebetween. At least first and second insulation-displacement portions project into the wire-receiving space from the respective first and second side walls. A wire can be pushed transversely into the wire-receiving space. Thus, the insulation-displacement portions cut the resin coating of the wire and contact the core of the wire.
Each insulation-displacement portion comprises two longitudinally spaced bases formed by bending or embossing the corresponding side wall inwardly. Each insulation-displacement portion further comprises a blade formed by folding and projecting portions of the side walls further inwardly from the bases. The insulation-displacement portions are configured and dimensioned so that only the blades bite into the resin coating. The bases of each insulation displacement portion may project and converge in a V-shape from the side walls when viewed in the wire pushing direction, and thus the bases restrict pulling or pushing forces on the wire.
In one embodiment, the bases may be L-shaped when viewed in the wire pushing direction. In other embodiments, the bases may be arcuate when viewed in the wire pushing direction. For example, the bases may have concave surfaces that face into the wire receiving space, and hence the bases may be configured to bulge arcuately in directions closer to each other. Alternatively, the bases may have convex surfaces that face into the wire-receiving space, and hence the bases may be arcuately configured to bulge away from each other.
Blades formed by folding a pair of blade panels are brought sharply into contact with the resin coating when the wire is pushed between the insulation-displacement portions. As a result, the resin coating is cut open reliably and with relative ease. Longitudinal pushing or pulling forces on the wire after connection with the insulation-displacement portions are restricted by the bases that project from the side walls in two positions. Thus, loose movement of the wire in its longitudinal direction can be prevented.
Only the narrow folded blade panels are brought sharply brought into contact with the resin coating while the wire is being pushed between the insulation-displacement portions. Thus, a contact error resulting from the coating getting caught or hooked by the wide bases can be avoided.